Looking for a light that changes color to match the color of the sun

[IdoVingX]

Hello all! This is my first post on the forum, so it's good to meet you!

I'm trying to find a light I can mount in my bedroom that changes color temperatures throughout the day to match the color temperature of the sun. I did some searching online and couldn't find one that existed to buy. In that case, I figured I would try building one!

My best idea is to use a color tunable LED (I found one here, but would love some suggestions since I'm not sure if this is a good one. http://www.environmentallights.com/14263-ctrf3528-120-8-foot.html) and make my own custom dimmer, probably using an Arduino to control the dimmer based on time of day.

Since I'm not a lighting expert (I'm a programmer) my biggest hurdle is choosing the right light. Assuming this product doesn't exist to buy, do you guys have any suggestions on what kind of color tunable light fits my purpose, is bright enough to light a room, and not too expensive?

Thanks in advance!

Ido

 

[StarHalo]

I'm not a big interior lighting guy, but just off the top of my head, I would think it'd be easier to do a fiber optic install that would "pipe in" exterior light, as opposed to building an entire LED array from scratch that could move across the Kelvin scale.

 

[Gunner12]

You could use light pipes, less energy used (sun light!) but maybe a bit of around the house work to get to the light. The problem is that the room will dim as the sun goes down. Maybe have something to detect the light level and add more light to compensate?

If you want to build a light that changes color temperature, maybe have a few sets of LEDs. A set of cool white ones, neutral white ones, and warm white ones and hook them to a switch, like a high power MOSFET or something. Wire each gate of the MOSFET to a digital IO pin of the microcontroller. I'l be nice if that pin is able to do PWM.

As the sun is rising, the warm white LEDs will turn on first. Low duty cycle PWM at first, so simulate the sun rising. Increase the duty cycle as the sun rises until the LEDs are fully on. The as the sun rises and the color gets cooler, decrease the duty cycle of the warm white LEDs and increase the duty cycle of the neutral white LEDs. For example, for each "tick" of duty cycle the warm whites loose, the neutral whites gain one "tick" of duty cycle. Do the same to the cool white LEDs as the sun gets even cooler as noon approaches. When the sun begins to go down, reverse the process and increase the duty cycle of the neutral whites and decrease the duty cycle of the cool whites and so on. Also have a setting for all LEDs to be on, just to kinda show off.

Maybe I should look at consulting jobs 😛

:welcome:

 

[Jabberwocke]

If your computer is in the same room there is a Windows program call "F.lux" that alters your monitor color balance to follow the local sun

 

[ElectronGuru]

If your computer is in the same room there is a Windows program call "F.lux" that alters your monitor color balance to follow the local sun

Wow, excellent suggestion. Never seen to many positive comments for an app.

Also for Linux, Mac, and [jailbroken] iPhone/Pad/Touch:

http://stereopsis.com/flux/


Edit, also a well written guide for CRI:

http://stereopsis.com/fullspectrum/

 

[Soames]

What sort of light are you looking for?
Brightgreen is an Australian company who are planning to market a domestic downlight which can change colour temperature and brightness. The product looks to be called the "Touch". You can find a pdf brochure on their downloads web page.

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They also used to market a device called a light harvester which you would mount in the ceiling and always keep the room at a preset brightness. It adjusts the output of connected downlights according to the amount of ambient light. When the light level falls outside the interior light increases and vice versa.